Over the past decades, the evolution of Investment Casting has focused on the production of larger and more complex components. This trend responds to the growing demand for technical sophistication in parts, partly driven by the innovation brought by MIM (Metal Injection Moulding) and Additive Manufacturing, which are now widely used for smaller-sized parts.

In this article, we explore how part types have evolved since the founding of Ecrimesa Group, when each technology is most efficient, and the rules to consider when designing or ordering parts made with Investment Casting.

How investment casting has evolved at Ecrimesa Group

With more than half a century of experience in metal part manufacturing, Ecrimesa Group has seen firsthand how investment casting has adapted to market needs. In the 1970s, the focus was on small to medium-sized parts in relatively simple steels. By the 1990s and early 2000s, the range of available materials had broadened significantly, and we began producing increasingly intricate parts. Today, we cast components up to 20 kg, with highly complex geometries and tight tolerances.

The image below illustrates this transition, showing actual production samples from 1970, 1990, and 2010. These examples reflect not only a change in scale but also a growing sophistication in design, surface finish, and dimensional precision.

Why small parts are still relevant

Despite the trend toward larger and more complex geometries, investment casting continues to play a key role in the production of small metal parts, especially those weighing less than 100 grams. While MIM and additive manufacturing are often considered first for this size range, investment casting remains the preferred solution in many technical scenarios.

For example, components with demanding mechanical properties, such as safety-critical parts, benefit from the superior material integrity of investment casting. Likewise, certain steels not yet available in MIM-compatible formats can be successfully processed with casting techniques. When it comes to low-volume production, the reduced tooling cost makes investment casting economically viable, especially for prototyping phases or market testing.

Moreover, investment casting offers greater design freedom. Unlike MIM, which requires flat support surfaces for sintering, cast parts can include complex, unsupported geometries. And when combined with 3D-printed wax patterns, investment casting becomes a powerful tool for rapid prototyping, without the need to build permanent molds upfront.

Choosing the right technology

The figure below compares several manufacturing technologies, investment casting, MIM, machining, sand casting, and powder metallurgy, based on part complexity and production volume. At Ecrimesa Group, we rely on investment casting, metal injection molding, machining, and additive manufacturing to apply the most efficient process in each case.

Investment casting typically excels in producing mid-sized, complex parts in mid-to-large volumes, while MIM is better suited for high volumes of small, high-precision components. Additive manufacturing is ideal for highly customized pieces or short production runs with geometric features that would be impossible to mold.

Materials suitable for investment casting

One of the greatest strengths of investment casting is its compatibility with a wide range of alloys:

• Carbon and low-alloy steels: C45, 42CrMo4, 16MnCr5
• Tool steels: 1.2363 for cold work, 1.2343 for hot work, 1.3343 for high-speed cutting
• Stainless steels: from ferritic (e.g. X12CrMoS17) and martensitic types to austenitic (1.4408), duplex (1.4582), and precipitation-hardening steels (17-4PH)
• Heat-resistant alloys: like 1.4841 for exhaust or high-temperature environments
• Aluminium: for lightweight parts requiring good corrosion resistance

At Ecrimesa, our team can also develop custom materials tailored to specific performance requirements or compliance standards, including those needed in aerospace (EN9100), defense, or medical sectors.

Design considerations and production limits

To ensure the part is viable for investment casting, it’s important to understand the limitations of the production process:

• Injection: Mold size must fit within the dimensions of the wax injection machine (up to ~550 mm).
• Coating: The size of slurry tanks and fluidized beds limits the volume of ceramic coating that can be applied uniformly.
• Casting: The ceramic molds must pass through preheating furnaces, which sets further dimensional constraints.

In our current setup, we manufacture parts from 1 gram up to 20 kg, with flat parts reaching up to 650 mm in length. For reference, parts with complex geometries often fall within a 300 mm cube. These ranges allow us to serve both precision applications and heavy-duty components.

Dimensional tolerances

Ecrimesa applies dimensional tolerances in accordance with the VDG P690 standard. Most parts fall within D2 class (general investment casting), but tighter tolerances like D3-A3 are also possible with secondary operations such as machining. Understanding these classifications is key when planning for assemblies or mating parts.

Best practices in design

Some general guidelines for designing parts for investment casting include:

• Minimum wall thickness: 2 mm in steel, 1.5 mm in aluminium
• Avoid sharp corners and abrupt section changes: These increase the risk of cracks or warping
• Add support features: Tie rods or radii help control deformation
• Design for flow: Avoid dead-end holes and incorporate gentle curves and tapers where possible
• Plan for cores if needed: Internal cavities can be achieved using ceramic or soluble wax cores

We work closely with customers during the design phase to optimize parts for both performance and manufacturability.

The following figure shows various practical recommendations for design:

Surface finish options

Surface quality depends on the post-casting process. We offer:

• As-cast or shot-blasted finishes: Ideal for functional parts
• Honing and polishing: For applications with cosmetic or tight roughness requirements
• Machining: For final tolerance control or aesthetic detailing

A combination of finishing operations can be used depending on the part’s final application, for example, a visible automotive component may be honed and machined, while a structural bracket may only require shot blasting.

A versatile solution for today’s manufacturing challenges

Investment casting remains a cornerstone of Ecrimesa Group’s manufacturing capabilities. Thanks to its versatility in materials, part complexity, and batch size, it’s often the optimal choice when precision, mechanical performance, and cost-efficiency are required — even in a world increasingly adopting MIM and 3D printing.

Whether you need a short-run prototype or a long-term production solution, our team can help you evaluate the best approach and support you throughout the design and manufacturing process.